The oldest human ancestors to have walked on the British Isles left nothing except footprints. But they've made quite an impression on the world of science.

Researchers say 50 or so prints found on a beach near the village of Happisburg in Norfolk are the oldest known human footprints outside Africa. They were discovered last spring by a team of experts from the British Museum, the Natural History Museum and Queen Mary University of London.

The footprints are thought to be those of Homo antecessor, or Pioneer Man. The findings are published in the latest issue of PLOS ONE.

It's thought that the impressions were made by a group of at least two large adult males, two or three adult females or teenagers and at least three or four children. The early humans would have gazed out at the north entrance to the English Channel as they strolled along the shore sometime between 800,000 and 1 million years ago.

The footprints represent "one of the most important archaeological discoveries ever made in Britain," The Independent writes.

They were discovered in a 430-foot-square area of shoreline at low tide, as heavy waves briefly washed away the silt to expose the prints.

The newspaper says:

"Archaeologists are now analysing detailed 3D images of the prints to try to work out the approximate composition of the group. Of the 50 or so examples recorded, only around a dozen were reasonably complete — and only two showed the toes in detail. Tragically, although a full photogrammetric and photographic record has been made, all but one of the prints were rapidly destroyed by incoming tides before they could be physically lifted. ...

"Archaeologists are now trying to determine the precise age of the footprints. They have so far succeeded in narrowing it down to two possible dates — around 850,000 years ago or 950,000 years ago. Only intense further study will reveal which of those two alternatives is the correct one."

[Add at 1:10 p.m. ET: It appears that the prints were not in fossilized rock but instead in hard-packed estuary mud, which would explain how they were washed away. In the PLOS ONE abstract, it's described as "laminated sediment."]

British Museum archaeologist Nick Ashton was quoted in the journal saying the fossilized footprints are "a tangible link to our earliest human relatives."

University of Southampton archaeology professor Clive Gamble, who was not involved in the project, called the discovery "tremendously significant," according to The Associated Press.

"This is the closest we've got to seeing the people," he told the AP.

"When I heard about it, it was like hearing the first line of [William Blake's hymn] 'Jerusalem' — 'And did those feet, in ancient time, walk upon England's mountains green?' Well, they walked upon its muddy estuary."